The estimate released on Thursday by the Centers for Disease Control and Prevention shows an overall increase of about 25 percent since the last analysis which was conducted in 2006 and a near-doubling of the rate reported in 2002.
According to CDC, among boys, the rate of autism spectrum disorders is one in 54, almost five times that of girls, in whom the rate is one in 252. No one knows why boys are at higher risk.
The largest increases in autism cases were found among black and Hispanic children, who have lagged behind whites in previous counts. “One thing the data tells us with certainty – there are many children and families who need help,” CDC Director Thomas Frieden said at a press conference.
The estimates show more children are being diagnosed at younger ages — average age at diagnosis has dropped from 4½ to 4, writes USA Today. “We heard from many parents that they were concerned long before their child was diagnosed. We are working hard to change that,” says Mr Frieden.
The reason caused increases is also not clear. Autism cases could rise due to better counting or something in the environment — or a mixture of both.
At least some of the increase is due to better awareness and diagnosis, but “I don’t believe the whole thing is diagnostic,” says Peter Bearman, a Columbia University sociologist who studies autism rates in California. He says his data is consistent with the CDC’s.
“What we do know for certain is autism is common and needs to be effectively served,” says Frieden. “We need to continue to increase the number of kids who are detected, detected early and enrolled in services early.”
Autism Speaks, an advocacy and research funding agency, claims that the results of the research show the U.S. needs to take fast action to help families and children on the spectrum, and invest in the kind of research that will help better explain why the numbers are rising so rapidly.
“Clearly we have a national emergency and clearly, we need a national plan,” said Mark Roithmayr, the group’s president. “It’s time for us as a nation to see these numbers for what they truly are, and for us as a nation to commit to doing much more than we’ve done for date.”
“The CDC figures may alarm some people, but I’m confident they are an underestimate,” says Roy Richard Grinker, an anthropology professor at The George Washington University in Washington, D.C.
Irva Hertz-Picciotto, a professor of the University of California Davis’ M.I.N.D. Institute, suggested that the government and private groups haven’t spent enough money researching possible environmental contributors to autism.
“So much of the funding has gone toward genetics that the environment has hardly been looked at and yet we already have several clues,” she explained. “We also need to think about prevention and that’s where the environmental concerns are so, so critical.”
Study conducted by Hertz-Picciotto and others shows that air pollution, nutrition, medications and toxic chemicals might all be contributing to the rise in autism rates.
“While we’re not completely sure of what is driving the rise in autism cases, it is certainly striking enough to warrant exploring in detail the possibility that environmental exposures contribute to this,” said Marc Weisskopf, an epidemiologist and associate professor at the Harvard School of Public Health.
“There are plenty of other reasons to avoid chemical toxicants, but we can’t yet pinpoint whether one of these is a culprit in this rise.”
In the nearest future the CDC plans to use its autism surveillance network to examine rates of cerebral palsy, intellectual disabilities and vision problems.
Knowing the rates of other conditions will help put the autism in a broader context, said Susan Levy, a developmental pediatrician at the Children’s Hospital of Philadelphia, who is involved in the research. “If everything is increasing, it gives you perspective.”